1. Field of the Invention
The present invention relates to a digital broadcast receiving apparatus and a method thereof.
2. Description of the Related Art
With the development of digital broadcasting technology and mobile communication technology, the provision of digital broadcasts to a mobile user has become an increasing matter of concern. Digital multimedia broadcasting (hereinafter referred to as a “DMB”) is a broadcasting service that enables a user to view diverse multimedia broadcasts on multiple channels using a personal portable receiver or a mobile vehicle receiver. Particularly, the satellite DMB adopted in Korea selects a CDM (Code Division Multiplexing) technology that is similar to a CDMA mobile phone as the Standard Rec. BO.1130-4: System-E of ITU (International Telecommunication Union).
In existing digital broadcast receiving apparatuses, a buffer is filled with broadcasting program data before providing the program to the user through a speaker and a display unit. The time it takes to actually view a selected program includes the time it takes to respond to user input, via a keypress, plus the time it takes to buffer the program. In effect, the time required for selecting the broadcasting channel in the digital broadcasting corresponds to the size of the buffer.
In such a DMB system, a plurality of broadcasting channels having different bit rates may be allocated to one transmission channel. For example, in the case of an audio broadcasting, four broadcasting channels of 64 Kbps, 48 Kbps, 48 Kbps and 32 Kbps are allocated to a certain transmission channel, and four broadcasting channels of 48 Kbps, 40 Kbps, 32 Kbps and 32 Kbps are allocated to another transmission channel. The minimum bit rate of the broadcasting channel is 24 Kbps.
For practical applications, the digital broadcast receiving apparatus should include a buffer sufficient for the largest bit rate. For example, a buffer having a size corresponding to the buffering of the 64 Kbps broadcasting channel data for two seconds requires a 5.33-second buffering time in buffering the 24 Kbps broadcasting channel data. If the time required to fill half of this buffer with the 64 Kbps broadcasting channel data is one second, the time required to fill half of this buffer with the 24 Kbps broadcasting channel data is 2.67 seconds.
As described above, in the digital broadcast receiving apparatus, the buffer-filling times are different from one another according to selected broadcasting channels, and this causes the waiting time (time to output the broadcasting channel data) to be different according to the selected broadcasting channel. Where the audio broadcasting channel buffer for the maximum bit rate is also used for the minimum bit rate, it increases the waiting time for broadcasting channel selection and output.